1、Designation: D4646 16Standard Test Method for24-h Batch-Type Measurement of Contaminant Sorption bySoils and Sediments1This standard is issued under the fixed designation D4646; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the y
2、ear of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method describes a procedure for determiningthe sorption affinity of waste solutes by unconsolidated
3、geo-logic material in aqueous suspension. The waste solute may bederived from a variety of sources such as wells, underdrainsystems, or laboratory solutions such as those produced bywaste extraction tests like the Test Method D3987 shakeextraction method.1.2 This test method is applicable in screeni
4、ng and provid-ing relative rankings of a large number of geomedia samplesfor their sorption affinity in aqueous leachate/geomedia sus-pensions. This test method may not simulate sorption charac-teristics that would occur in unperturbed geologic settings.1.3 While this procedure may be applicable to
5、both organicand inorganic constituents, care must be taken with respect tothe stability of the particular constituents and their possiblelosses from solution by such processes as degradation bymicrobes, light, hydrolysis, or sorption to material surfaces.This test method should not be used for volat
6、ile chemicalconstituents (see 6.1).1.4 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user
7、 of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E11 Specification for Woven Wire Test Sieve Cloth and TestSievesD5681 Terminology for Waste and Waste ManagementD
8、1193 Specification for Reagent WaterD2216 Test Methods for Laboratory Determination of Water(Moisture) Content of Soil and Rock by MassD3987 Practice for Shake Extraction of Solid Waste withWaterD4319 Test Method for Distribution Ratios by the Short-Term Batch Method (Withdrawn 2007)3E2551 Test Meth
9、od for Humidity Calibration (or Conforma-tion) of Humidity Generators for Use with Thermogravi-metric Analyzers3. Terminology3.1 Definitions:3.1.1 For definition of terms used in this test method refer toTerminology D5681.3.2 Definitions of Terms Specific to This Standard:3.2.1 distribution coeffcie
10、nt, Kdthe ratio of the concentra-tion of solute sorbed on the soil or other geomedia divided byits concentration in solution. A 24-h Kdis the analogous ratioevaluated after 24 h of contact of the solute with the geomedia.3.2.1.1 DiscussionThe dimensions of Kdreduce to unitsof volume per mass. It is
11、convenient to express Kdin units ofmilliliters (or cubic centimeters) of solution per gram ofgeomedia. Dissimilar Kdvalues may be obtained if differentinitial solute concentrations are used, depending on the sorp-tion behavior of the solute and the properties of the geomedia(that is, nonlinear sorpt
12、ion curve). This concentration depen-dency may be absent where the solute concentrations aresufficiently low or the characteristics of the particular solute-sorbent combination yield Kdvalues that are independent of theconcentration of solute (that is, linear sorption curve).3.2.2 solutea chemical s
13、pecies (for example, ion,molecule, etc.) dissolved in a solution.3.2.3 sorbatea chemical species retained by a sorbent.1This test method is under the jurisdiction of ASTM Committee D34 on WasteManagement and is the direct responsibility of Subcommittee D34.01.04 on WasteLeaching Techniques.Current e
14、dition approved Sept. 1, 2016. Published November 2016. Originallyapproved as ES 10 85. Last previous edition approved in 2008 as D4646 03(2008). DOI: 10.1520/D4646-16.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual
15、 Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United St
16、ates13.2.4 sorbenta solid medium (for example, soil, sediment,till, etc.) in or upon which solutes are collected by absorptionor adsorption.3.2.5 sorptiona physical and chemical process by which asorbate is taken up or held (that is, sorbed) to a sorbent by acombination of adsorption and absorption.
17、3.2.6 sorption affnitythe relative degree of sorption thatoccurs between a solute and a sorbent.3.2.7 unconsolidated geologic material (geomedia)aloosely aggregated solid natural material of geologic origin (forexample, soil, sediment, till, etc.).4. Summary of Test Method4.1 Distilled water, natura
18、l water, waste leachate, or otheraqueous solution containing a known concentration of a soluteis mixed with a known amount of unconsolidated geologicmaterial (geomedia) for 24 h, after which equilibrium betweenthe sorbent and solution phase is presumed to occur. Thesorbent-to-solution ratio for this
19、 test is 1:20 on a mass basis.The concentration of solute remaining in solution is measuredand the amount of solute adsorbed is calculated by differencewith the known concentration in the initial solute. Given thatthe mass of solid phase is known, the distribution coefficient,Kd, for the specified e
20、xperimental conditions can then becalculated.5. Significance and Use5.1 This test method is meant to allow for a rapid (24 h)index of a geomedias sorption affinity for given solutes inenvironmental waters or leachates. A large number of samplesmay be run in parallel using this test method to determi
21、ne acomparative ranking of those samples, based upon the amountof solute sorbed by the geomedia, or by various geomedia orleachate constituents. The 24-h time is used to make the testconvenient and also to minimize microbial, light, or hydrolyticdegradation which may be a problem in longer-timed pro
22、ce-dures. While Kdvalues are directly applicable for screeningand comparative ranking purposes, their use in predictive fieldapplications generally requires the assumption that Kdbe afixed value.5.2 While this test method may be useful in determining24-h Kdvalues for nonvolatile organic constituents
23、, interlabo-ratory testing has been carried out only for the nonvolatileinorganic species, arsenic and cadmium (see Section 12).However, the procedure has been tested for single laboratoryprecision with polychlorinated biphenyls (PCBs) and is be-lieved to be useful for all stable and nonvolatile ino
24、rganic, andorganic constituents. This test method is not considered appro-priate for volatile constituents.5.3 The 24-h time limit may be sufficient to reach asteady-state Kd; however, the calculated Kdvalue should beconsidered a non-equilibrium measurement unless steady-statehas been determined. To
25、 report this determination as a steady-state Kd, this test method should be conducted for intermediatetimes (for example, 12, 18, and 22 h) to ensure that the solubleconcentrations in the solution have reached a steady state by 24h. If a test duration of greater than 24 h is required, refer to TestM
26、ethod D4319 for an alternate procedure of longer duration.6. Interferences6.1 When dealing with solutes of unknown stability either incontact with the geomedia or when used as blanks, care mustbe taken to determine if volatilization, hydrolysis,photodegradation, microbial degradation, oxidation-redu
27、ction(for example, Cr3+to Cr6+) or other physicochemical processesare operating at a significant rate within the time frame of theprocedure. The stability and hence loss from solution mayaffect the outcome of this procedure if the aforementionedreactions are significant.6.2 Although efforts should b
28、e taken to find equipmentmade with contact surface materials compatible with the solutesolution, solute losses may occur due to sorption to materialsurfaces. Thus, method blanks (that is, solutes carried throughthe process with sorbents) should be conducted.6.3 The compatibility of the method and th
29、e solute ofinterest may be assessed by determining the differences be-tween the initial solute concentration (see 9.8) and the finalmethod blank concentration of the solute (see 9.16). If thisdifference is greater than the expected precision of the method(10 %), then the Kdvalue generated may be unr
30、eliable andmust be carefully evaluated.7. Apparatus7.1 Agitation EquipmentA device of any type that rotatesabout a central axis at a rate of 29 6 2 revolutions per minuteand mixes samples in an end-over-end fashion (see TestMethod D3987).7.2 Phase Separation EquipmentA filtration apparatusmade of ma
31、terials compatible with the solutions being filteredand equipped with a 0.45-m pore size membrane filter, or aconstant temperature centrifuge capable of separating particleswith diameters greater than 0.1 m (see Section 9). If organiccompounds are being measured, the filtration apparatus, cen-trifug
32、e tubes etc., should be compatible with the compoundsbeing measured (for example, glass or stainless steel). Sorptionof solute onto the filtration membrane may be significant forsome solutes, and must be evaluated by the use of blanksthrough all steps of the procedure.7.3 ContainersRound, wide-mouth
33、 bottles compatiblewith the rotary extractor and of composition suitable to thenature of the solute(s) under investigation and the analysis tobe performed will be used. For nonvolatile inorganicconstituents, high-density polyethylene bottles should be usedwith the size of the bottle dictated by samp
34、le size, and the needfor the solution to occupy 70 to 80 % of the container volume(that is, 125, 250, or 2000-mL bottles for sample sizes of 5, 10,or 70 g respectively). For nonvolatile organic constituents,glass bottles, or stainless steel containers with water-tightclosures made of chemically iner
35、t materials should be usedwith size requirements being the same as for nonvolatileinorganics. Containers should be cleaned in a manner consis-tent with the analyses to be performed. Samples of thesolutions to be analyzed should be stored in similar chemicallycompatible bottles.D4646 1627.4 Balance,
36、having a capacity of at least 70 g and asensitivity of 60.005 g shall be used.7.5 Mortar and Rubber-tipped PestleApparatus suitablefor breaking up aggregations of air-dried soil particles withbreaking individual particles.7.6 SieveNo. 10 (2 mm) brass or stainless steel wire meshsieve that conforms t
37、o the requirements of Specification E11.7.7 ThermometerA gravity thermometer conforming tothe requirements of Specification E2551.8. Reagents8.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the speci
38、fications of theAmericanChemical Society, where such specifications are available.4Other grades may be used, provided it is first ascertained thatthe reagent is of sufficiently high purity to permit its usewithout lessening the accuracy of the determination.8.2 Purity of WaterUnless otherwise indica
39、ted, referencesto water shall be understood to mean reagent water meeting thecriteria of Type IV in Specification D1193.9. Procedure9.1 Geomedia samples are spread out on a flat surface, nomore than 2 to 3 cm deep, and allowed to air dry for 7 days oruntil constant weight (a change that is less than
40、 5 % over a 24-hperiod) is achieved. Do not oven dry the geomedia.9.2 After the sample has air dried, it is passed through a2-mm screen sieve. Large aggregates are to be crushed, withoutgrinding, using a clean mortar and a rubber-tipped pestle. Themass fraction of irreducible material greater than 2
41、-mm shouldbe noted and removed from the geomedia sample.9.3 Mix the sieved material until the sample is homoge-neous. Use a riffle splitter, or other unbiased splittingprocedure, to obtain subsamples of appropriate size.9.4 Remove subsamples and determine the moisture contentof the air-dried sample
42、(refer to Test Method D2216).9.5 Determine the mass of geomedia sample, corrected formoisture content:Determination of air-dried soil mass equivalent to the desiredmass of oven-dried soil:A 5 Ms11M/100! # (1)where:A = air dry soil massMs= mass of oven-dried soil desired, andM = moisture, %.9.6 Place
43、 between 5 and 70 g (oven-dried basis) of theweighed air-dried sample into the appropriate container. Thesamples should be weighed to a minimum of three significantfigures (see 7.3).9.7 Add to the container an amount of solute solutionnecessary to yield a 1:20 sorbent-to-solution ratio on a massbasi
44、s using the oven-dried geomedia mass:Determination of solution volume needed per sample for asorbent-to-solution ratio of 1:20:V 5 Ms320!/ (2)where: = density of solution, g/cm3,V = volume of solution per sample, cm3, andMs= mass of geomedia to be used, g, (oven-dried basis).9.8 Retain a separate, a
45、ppropriately preserved aliquot foranalysis of the initial solute concentration.9.9 Method blanks may be prepared by placing the samevolume of solute solution into an empty container withoutgeomedia. These blanks should be carried through the entireremainder of the procedure including agitation, filt
46、ration, orcentrifugation and analysis.9.10 Close the container and place it on the rotary extractor.9.11 Agitate continuously for 24 6 0.5hat296 2 r/min atroom temperature (22 6 5C).9.12 Open the container. Note the temperature of the solu-tion and any changes in the sample or solution (that is, col
47、or,odor, etc.).9.13 Separate the solution phase from the majority of thesolid phase by decantation.9.14 Filter the solution phase through a 0.45-m pore sizemembrane filter (see 7.2), or centrifuge a subsample at thepredetermined rate of rotation and time for the centrifugationequipment employed at c
48、onstant temperature (the temperaturerecorded after 24 h):t 5 9/2S2rp2p2 !DlnRb/Rt!(3)where:2=42r/min!2605 angular velocity,rp= particle radius, cm, = viscosity of water, 8.95 103g/s-cm at 25C,p= particle density, = density of solution,r/min = revolutions per minute,Rt= distance from center of centri
49、fuge rotor to top ofsolution in centrifuge tube, cm,Rb= distance from center of centrifuge rotor to bottom ofcentrifuge tube, cm, andt = time, min.To remove particles 0.1-m radius and 2.65-g/cm3densityfrom solution:t 5S3.71 3108r/min!2 DlnRb/Rt! (4)4Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States P
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